Method of expanding a pliable material

ABSTRACT

A method has the following general steps for expanding a continuous length of a pliable material so that originally parallel and straight lateral edges thereof are stretched to curved configurations of different arc lengths. A continuous length of the material is unwound and heated to a temperature at which the material is pliable. The material is expanded between a first line which is both located on a surface of a first object and perpendicular to the lateral edges of the material, and a second line which is located on a surface of a second object, which second line is coplanar with the first line but in skew relationship thereto. The expanded material is continuously moved along a substantial length of the second object&#39;&#39;s surface. The expanded material is cooled while in engagement with the second object&#39;&#39;s surface to a temperature at which the material is sufficiently rigid that it may be removed and cut to finite lengths to form the desired article.

United States Patent Stark et al.

1541 METHOD or EXPANDING A PLIABLE MATERIAL [72] Inventors: John E.Stark, London, England;

Adrian G. Vanoostveen, Niagara Falls, Ontario, Canada [73] Assignee: FodMotor Company, Dearbom,

Mich.

[22] Filed: Feb. 3, 1970 211 App]. No.: 8,213

[30] Foreign Application Priority Data Nov. 28, 1969 Canada ..68584 52U.S.Cl. ..264/292, 264/160, 264/288, 5 264/291 51 1m. 01. ..B28b 11/08,B29c 17/02 [58] Field of Search ..264/ 160 VG, 291 VG, 89, 326, 264/295,292, 237, 348, 288; 18/1 FS, l FB,

[4 1 Oct. 3, 1972 3,058,160 10/1962 Mocker et al. ..264/292 3,244,7794/1966 Levey et al. ..264/291 3,293,343 12/1966 Mattimoe et al...264/291 3,354,253 1 l/ 1967 Rasmussen ..264/29l 3,419,651 12/1968Miller et al. ..264/291 Primary Examiner-Jay H. Woo Attorney-John R.Faulkner and William E. Johnson [57] ABSTRACT A method has the followinggeneral steps for expanding a continuous length of a pliable. materialso that originally parallel and straight lateral edges thereof arestretched to curved configurations of different arc lengths. Acontinuous length of the material is unwound and heated to a temperatureat which the material is pliable. The material is expanded between afirst line which is both located on a surface of a first object andperpendicular to the lateral edges of the material, and a second linewhich is located on a surface of a second object, which second line iscoplanar with the first line but in skew relationship thereto. Theexpanded material is continuously moved along a substantial length ofthe second objects surface. The expanded material is cooled while inengagement with the second object's surface to a temperature at whichthe material is sufficiently rigid that it may be removed and cut tofinite lengths to form the desired article.

10 Claims, 3 Drawing Figures METHOD OFEXPANDING A PLIABLE MATERIALBACKGROUND OF THE INVENTION Various methods and apparatuses have beendevised for use in stretching the vinyl material having a tinted bandthat is utilized as a laminating layer between the glass bracketsutilized to form an automotive windshield. Some typical prior .artapparatuses and methods are shown in U.S. Pat. No. 2,933,759 issued Apr.26, 1960, and US. Pat. No. 3,0l9,'475 issued Feb. 6, i962.

The above two mentioned patents disclosemethods and apparatuses ofstretching a plasticized polyvinyl butyral web utilized to form theinterlayer of an automotive windshield. The stretching of such materialis necessary when a tinted band is placed along one lateral edge ofthematerial so that the material may be utilized in the formation of atinted windshield for an automotive vehicle. More particularly, thetinted band or gradient band is locatedat the top of the windshield inorder to reduce the light transmission capability of the windshield inthat area. This reduction in light transmission aidsthe operator of thevehicle by reducing the amount of glare he is subjected to, therebyimproving his field of vision.

When the gradient band windshield has both horizontal and verticalcurvature, it is necessary to stretch each interlayer prior to placingit between two glass brackets. This stretching is necessary so that uponlamination of two glass brackets with the interlayer, the edge of thegradient band across the windshieldwill ap pear as a straight line whenthe windshield is assembled in an automobile. In its stretchedcondition, the interlayer will have thelateral edges thereof formed intocurved configurations with different are lengths. To facilitate themanufacture of the interlayer material, the material is produced inlarge rolls with'the lateral edges thereof in a parallel and straightcondition. Many individual interlayers may be formed from one such largeroll of material.

both located on the surface of a first object and perpendicular to thelateral edges of the material, and a second line located on a surface ofa second object, which second line is coplanar with the first line butin skew relationship thereto. A differential section of the expandedmaterial is continuously moved away from the second line on the secondobject by moving the expanded material both along the surface of thesecond object and over a substantial length of the total surface areadefined by the second object. While moving along the surface areadefined by the second object, the expanded material is cooled to atemperature at which the material is no longer pliable but issubstantially rigid. A differential section of the expanded material iscontinuously removed from the second surface of the second object andfinite lengths of the material are cut from the removed material. Eachfinitelength of the material serves as one interlayer and it has itslateral edges stretched to curved configurations of different arelengths.

In greater detail, the first object is a rotatable cylindrical roll andthe second object is a rotatable conical roll. In still further detail,the conical roll is defined by a plurality of spaced apart membersextending generally across the width of the material and the cooling ofthe stretched material is accomplished by directing separate streams ofa chilling fluid against both sides of the material as the materialpasses along the conical The above two mentioned patents show 'methodsand the present method is much simpler and less costly in operation.

SUMMARY OF THE INVENTION This invention relates to a method of expandinga continuous length of material and, more particularly, to a method ofexpanding a continuous length of a vinyl interlayer material utilized informing a gradient band windshield for an automotive vehicle. The methodof this invention is carried out in the following manner.

A continuous length of a material having originally parallel andstraight lateral edges is unwound from a roll thereof so that thematerial may be stretched to a final configuration in which the edges ofthe material are curved with opposite lateral edges having a dif ferentarc length. Once unwound, a differential section of the material iscontinuously heated to a temperature at which the material issufficiently pliable for stretching. A differential section of :theheated material is continuously expanded between a first line that issurface area defined by the second object. In still further detail, theoriginal heating of the material is done in a fashion such that onesurface of the material is heated to a temperature higher than the othersurface, the higher temperature surface being the surface which does nothave a tinted or gradient band therealong.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graphic view of awindshield formed with an interlayer stretched by the method of thisinvention.

FIG. 2 is a diagrammatic, elevational view, partly in cross section, ofapparatus employed in the method of this invention.

. FIG. 3 is a front view of a-portion of the apparatus shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the formation of anautomotive safety windshield, a pair of glass brackets are laminatedtogether with an interposed sheet of a plasticized polyvinyl butyral.The glassbrackets have an approximate thickness of 0.125 inch and theinterlayer has a thickness of approximately 0.030 inch. The formation ofsuch a laminated assembly is well known in the art.

In many cases, it is desirable to include in the laminating interlayer adarkened or gradient tint band at the top portion thereof to reduce theamount of light which is allowed to enter into the automotive vehiclethrough the top portion of the windshield. With reference to FIG. 1,this particular band is generally known as the gradient band 5 andpreferably is graduated with the intensity of coloration decreasing fromthe top 6 of the windshield 7 to a position 8 spaced from the bottom 9thereof. Because most modern day automotive Windshields have both ahorizontal and a vertical curvature thereto, it is necessary to stretchthe gradient vinyl to the proper curvature prior to laminating the vinylwith the pair of glass brackets. More particularly, in order that theend of the gradient tint line 8 in the windshield appear as a uniformhorizontal line when the windshield is installed in an automobilevehicle, it is necessary to stretch the interlayer material so that theupper and lower edges thereof have a proper radius of curvature prior tothe lamination of the material. As shown in FIG. 1, the lower portion orline 8 of the gradient band 5 is not horizontal. However, when thewindshield 7 is installed in an automotive vehicle, the angle ofinstallation of the windshield will be such that the bottom of the bandwill appear as a straight line when viewed from the exterior of theautomobile. v

The vinyl material used for the interlayer, as purchased, is in acontinuous roll wherein the opposite lateral edges thereof are in asubstantially parallel relationship. As a final expanded product, finitelengths of the interlayer are formed from the roll in such aconfiguration that the upper and lower lateral edges of the interlayerare stretched to curved configurations of different arc lengths.Generally, the upper edge of the gradient band interlayer is of smallerarc length than the lower edge thereof.

The method of this invention will be understood best by reference to theassociated drawings. More particularly, with reference to FIG. 2 of thedrawings, a continuous roll of commercially available, polyvinyl butyral10 is shown as it is unwound. The roll of vinyl is formed so that oneedge thereof has a gradient, tinted band therealong. The tinted bandwould be facing upward and on the far side of the apparatus as viewed inFIG. 2.

The vinyl material is unrolled and put through a plurality of rinsingsolutions at a rinsing station 12. At the rinsing station, water isutilized to wash from the surface of the vinyl fine dust material whichis placed thereon in order to keep the various convolutions of thematerial in the roll 10 separate during its handling and shipping.

After passing through the washing and rinsing station 12, a differentialsection of the vinyl ribbon 10 is passed through a squeegee station 14wherein rollers and air jets are utilized to remove any excess moisturetherefrom. From the squeegee station, the vinyl ribbon is passed into aribbon heating station 16. In the heating station, a plurality of rolls18 are employed to support the web during its passage therethrough.Within the station are a plurality of upper heating elements 20 andlower heating elements 22. The heating elements may be employed in sucha manner as to uniformly heat the vinyl to a preselected temperature ofabout 170 F. at which the vinyl may be stretched. In the alternative,the heating pattern may be such that one surface of the vinyl is heatedto a greater temperature than the other surface. In this case, the uppersurface is heated to the lower temperature of about 150 F. so it will beat a temperature which would not affect the tinted band along the onelateral edge thereof.

The ribbon of vinyl passes from the ribbon heating station 16 through anopening in a partition wall 24 into another room which contains furtherprocessing equipment. The other room is maintained at both a preselectedhumidity and a preselected temperature so that the vinyl, after it iscut into individual interlayer pieces, may be stored for subsequentprocessing without the amount of moisture therein increasing.

As the ribbon passes through the opening in the partition 24, it passesaround a rotatable cylindrical or take-off roll 26 which is driven atthe same speed as the linear speed of movement of the vinyl material.The ribbon material departs from the cylindrical roll 26 along a firststraight line which is generally perpendicular to the lateral edges ofthe ribbon of vinyl 10. From the cylindrical roll, the ribbon of vinylis directed to a rotatable conical roll 28, best seen in FIG. 3.

The conical roll 28 has a large end 30 of about 30 inches in diameterand a small end 32 of about 24 inches in diameter. The desired angle ofthe cone may be adjusted by means of adjustable mechanism 34 operated bycrank 36 in a standard manner which would change the diameters of thecone. The exact angle of the cone determines the radius which isgenerated in both the upper and lower edges of the ribbon of vinyl 10passing thereover. More particularly, the stretching of the vinyl occursfrom its first line of contact leaving the cylindrical or take-off roll26 to a second line of contact on the conical roll 28. This second lineof contact is coplanar with the first or departing line of contact butin skew relationship thereto. Thus, as the web travels from thecylindrical roll 26 to the conical roll 28, it is differentiallystretched because of the difference in speeds found at the differentends of the conical roll. The small diameter end 32 of the cone isdriven at the same peripheral speed as the cylindrical roll and,therefore, that end of the material will not be stretched while the endof the vinyl material going over the large end 30 of the conical rollwill be stretched substantially. In the usual processing method, thetinted or gradient band portion of the ribbon is located near the smalldiameter end of the cone. The large diameter end of the cone applies agreater stretching action to the ribbon and thus permits the developmentof a greater radius in the bottom portion of the vinyl passingthereover.

Mounted above the conical roll 28 by suitable means, not shown, is adelivery pipe 38 for a cold air cooling system used to cool the vinyl onthe conical roll. The air fed through the pipe has a temperature ofapproximately 40 F. The delivery pipe contains an internal baffel 40,shown in FIG. 4, which divides the air flowing down the chamber or pipeinto two streams. The major portion of the air is flowed over the uppersurface of the web 10 as it rests on elements 42 making up the exteriorsurface of the conical member 38. These elements 42 are individual slatsabout one-sixteenth of an inch thick with seven-sixteenths of an inchbetween facing elements and they extend from the small end of theconical roll to the large end thereof. By such construction, a secondportion of the stream of cooling air which is delivered by the pipe 38flows down through the elements and along the side of the ribbon restingon the elements thereby cooling the inside surface of the web 10.

As best seen in FIG. 1, the ribbon, while laying on the moving conicalroll 28, is moved along a substantial portion of the surface areadefined by the conical roll 28 and is removed therefrom around atake-off roll 44,

at which time the vinyl has a temperature of about 70 F. From thetake-off roll 44, the ribbon is fed to a table 46 above which a cut-offmachine 48 is mounted. A portion of the ribbon is drawn under thecut-off machine by an operator and then the cut-off machine is movedover the table 46 thereby cutting off a finite length of the vinyl. Thisfinite length of vinyl will have the lateral edges thereof stretched tocurved configurations of different arc lengths.

OPERATION The operation of the apparatus utilized in conjunction withthe method of this invention will now be described in detail. A web ofcommercially available material formed from plasticized polyvinylbutyral is utilized as the interlayer material. This is commerciallyavailable in lengths of 800 and 1500 feet with various widths, e.g., ofabout 28.5 inches.

In making a particular interlayer wherein the vinyl had a width of 27inches, the rate of unwinding and washing of the vinyl material was at18 feet per minute. Similarly, the conical roll was driven at a speedsuch that the small diameter end 32 thereof was also travelling at arate of 18 feet per minute. The cone angle was set for theoreticalradiusof 83 inches to produce a curvature in the vinyl of 100 inches at theupper edge and 127 inches at the lower edge thereof.

The vinyl fed to the web heating station 16 was heated in such a mannerby the upper heating elements therein that the upper surface was heatedto a final temperature of 150 F. while the lower surface of the materialwas heated to a temperature of 170 F. The reason for the imbalance inthe temperatures to which the two surfaces are heated is that the uppersurface carries the tinted band and is more temperature sensitive thenthe lower surface of the vinyl. By differentially heating upper andlower surfaces of the vinyl, less heat must be removed by the flowing ofthe cooling air over the vinyl as it travels around the conical roll.The vinyl is cooled on the conical roll to a temperature of about 70 F.before it is removed therefrom and cut into finite lengths.

While the preferred embodiment of this invention has been described inconjunction with a gradient band vinyl material, it is understood thatthe method may also be applied to clear vinyl material not having atinted band therealong. When utilized with clear vinyl, a substantialcost savings is realized by this method because a narrower vinylmaterial may be utilized in forming the interlayer for individualWindshields.

We claim:

1. A method of expanding a continuous length of polyvinyl butyral sothat originally parallel and straight lateral edges thereof arestretched to curved configurations of different are lengths, whichmethod comprises:

unwinding a continuous length of the polyvinyl butyral;

heating continuously a differential section of the polyvinyl butyral toa temperature in the range of about 150 F, to about 180 F, so thepolyvinyl butyral is sufi'lciently pliable so that it may be stretched;

expanding continuously a differential section to the polyvinyl butyralby stretching the polyvinyl butyral while in a heated condition betweena first line located on the surface of a cylindrical roll andperpendicular to the lateral edges of the polyvinyl butyral and a secondline located on a surface of a rotatable conical roll defined by aplurality of spaced apart members, which second line is coplanar withsaid first line but in skew relationship thereto; moving continuously adifferential section of the expanded polyvinyl butyral away from saidsecond line on said conical roll by moving the expanded polyvinylbutyral along the surface of said conical roll defined by said spacedapart members and over a substantial length of the total surface areadefined by said conical roll; cooling the expanded polyvinyl butyralwhile the polyvinyl butyral is moving along said conical roll bydirecting streams of a chilling fluid against both sides of thepolyvinyl butyral as the polyvinyl butyral passes over the surface ofsaid conical roll, said polyvinyl butyral being cooled to a temperaturebelow about F, at which the polyvinyl butyral is no longer pliable butis substantially rigid;

removing continuously a differential section of the expanded polyvinylbutyral from said conical roll; and

cutting finite lengths of the polyvinyl butyral from the continuouslength thereof when removed from said conical roll, each finite lengthhaving lateral edges thereof stretched to curved configurations ofdifferent arc lengths.

2. A method of expanding a continuous length of a material so thatoriginally parallel and straight lateral edges thereof are stretched tocurved configurations of different arc lengths, which method comprises:

unwinding a continuous length of the material;

heating continuously a differential section of the material to atemperature at which the material is sufficiently pliable so that thematerial may be stretched;

expanding continuously a differential section of the material bystretching the material while in a heated condition between a first lineboth located on a surface of a first object and perpendicular to thelateral edges of the material and a second line located on a surface ofa second object, which second line is coplanar with said first line butin skew relationship thereto;

moving continuously a differential section of the expanded material awayfrom said second line on said second object by moving the expandedmaterial both along the surface of said second object and over asubstantial length of the total surface area defined by said secondobject;

cooling the expanded material while the material is moving along saidsurface area of said second object to a temperature at which thematerial is no longer pliable but is substantially rigid; removingcontinuously a difierential section of the expanded material from saidsecond object; and 7 cutting finite lengths of the material from thecontinuous length of material when removed from said second object, eachfinite length having lateral edges thereof stretched to curvedconfigurations of different arc lengths.

3. The method of claim 2 wherein: said first object is a rotatablecylindrical roll and said second object is a rotatable conical roll.

4. The method of claim 3 wherein said surface of said second object isdefined by a plurality of spaced apart members, and wherein said coolingis accomplished by directing streams of a chilling fluid against bothsides of the material as the material passes over the surface of saidsecond object.

5. The method of claim 4 wherein: said separate streams of said chillingfluid are formed by: initially establishing a single stream of chillingfluid; flowing said single stream toward the outer surface of saidsecond object; dividing said single stream into two substreams;directing one substream onto the outer surface of said second object tocool the outside surface of the material; directing a second substreamthrough the openings in said surface of said second object between saidspaced apart members which are not covered by the material; and flowingsaid second substream of chilling medium over the inside surface of thematerial supported on said surface of said second object; whereby bothsides of the expanded material are simultaneously cooled while movingover said surface of said second object.

6. A method of expanding a continuous length of a material having atinted band along a lateral edge of one side thereof so that originallyparallel and straight lateral edges thereof are stretched to curvedconfigurations of different arc lengths, which method comprises:

unwinding a continuous length of the material;

heating continuously to different temperatures the opposite surfaces ofa differential section of the material, the different temperatures beingsufficiently high that the material is pliable and may be stretched, thecooler surface of the material being the surface having the tinted bandalong the lateral edge thereof;

expanding continuously a differential section of the heated materialbetween a first line both located on a surface of a first object andperpendicular to the lateral edges of the material, and a second linelocated on a surface of a second object, which second line is coplanarwith said first line but in skew relationship thereto;

moving continuously a differential section of the expanded material awayfrom said second line on said second object by moving the expandedmaterial both along the surface of said second object and over asubstantial length of the total surface area defined by said secondobject;

cooling the expanded material while the material is moving along saidsurface area of said second object to a temperature at which thematerial is no longer pliable but is substantially rigid;

removing continuously a differential section of the expanded materialfrom said second object; and

cutting finite lengths of the material from the continuous length ofmaterial when removed from said second object, each finite length havinglateral edges thereof stretched to curved configurations of differentarc length.

7. The method of claim 6 wherein: said first object is a rotatablecylindrical roll and said second object is a rotatable conical roll andwherein the surface of the material heated to the cooler temperaturedoes not contact the surface of said second roll as the material passesthereover.

8. The method of claim 7 wherein: said surface of said second object isdefined by a plurality of spaced apart members extending laterallyacross the material, and wherein said cooling is accomplished bydirecting separate streams of a chilling fluid against both sides of thematerial as the material passes over said surface of said second object.

9. The method of claim 8 wherein: said separate streams of said chillingfluid are formed by: initially establishing a single stream of chillingfluid; flowing said single stream toward the outer surface of saidsecond object; dividing said single stream into two substreams;directing one substream onto the outer surface of said second object tocool the outside surface of the material; directing a second substreamthrough the openings in said surface of said second object between saidspaced apart members which are not covered by the material; and flowingthe second substream of chilling medium over the inside surface of thematerial supported on said spaced apart members defining the surface ofsaid second object; whereby both sides of the expanded material aresimultaneously cooled while moving along a substantial portion of saidsurface area of said second object.

10. The method of expanding a continuous length of polyvinyl butyral asdefined in claim 1 wherein: the polyvinyl butyral has a tinted bandalong a lateral edge of one side thereof, wherein said side having thetinted band therealong is heated to a temperature of about F, in saidheating step, and wherein said side not having the tinted bandtherealong is heated to a temperature of about F, in said heating step.

2. A method of expanding a contiNuous length of a material so thatoriginally parallel and straight lateral edges thereof are stretched tocurved configurations of different arc lengths, which method comprises:unwinding a continuous length of the material; heating continuously adifferential section of the material to a temperature at which thematerial is sufficiently pliable so that the material may be stretched;expanding continuously a differential section of the material bystretching the material while in a heated condition between a first lineboth located on a surface of a first object and perpendicular to thelateral edges of the material and a second line located on a surface ofa second object, which second line is coplanar with said first line butin skew relationship thereto; moving continuously a differential sectionof the expanded material away from said second line on said secondobject by moving the expanded material both along the surface of saidsecond object and over a substantial length of the total surface areadefined by said second object; cooling the expanded material while thematerial is moving along said surface area of said second object to atemperature at which the material is no longer pliable but issubstantially rigid; removing continuously a differential section of theexpanded material from said second object; and cutting finite lengths ofthe material from the continuous length of material when removed fromsaid second object, each finite length having lateral edges thereofstretched to curved configurations of different arc lengths.
 3. Themethod of claim 2 wherein: said first object is a rotatable cylindricalroll and said second object is a rotatable conical roll.
 4. The methodof claim 3 wherein said surface of said second object is defined by aplurality of spaced apart members, and wherein said cooling isaccomplished by directing streams of a chilling fluid against both sidesof the material as the material passes over the surface of said secondobject.
 5. The method of claim 4 wherein: said separate streams of saidchilling fluid are formed by: initially establishing a single stream ofchilling fluid; flowing said single stream toward the outer surface ofsaid second object; dividing said single stream into two substreams;directing one substream onto the outer surface of said second object tocool the outside surface of the material; directing a second substreamthrough the openings in said surface of said second object between saidspaced apart members which are not covered by the material; and flowingsaid second substream of chilling medium over the inside surface of thematerial supported on said surface of said second object; whereby bothsides of the expanded material are simultaneously cooled while movingover said surface of said second object.
 6. A method of expanding acontinuous length of a material having a tinted band along a lateraledge of one side thereof so that originally parallel and straightlateral edges thereof are stretched to curved configurations ofdifferent arc lengths, which method comprises: unwinding a continuouslength of the material; heating continuously to different temperaturesthe opposite surfaces of a differential section of the material, thedifferent temperatures being sufficiently high that the material ispliable and may be stretched, the cooler surface of the material beingthe surface having the tinted band along the lateral edge thereof;expanding continuously a differential section of the heated materialbetween a first line both located on a surface of a first object andperpendicular to the lateral edges of the material, and a second linelocated on a surface of a second object, which second line is coplanarwith said first line but in skew relationship thereto; movingcontinuously a differential section of the expanded material away fromsaid second line on said second object by moving the expanded materialboth along the surface of said second Object and over a substantiallength of the total surface area defined by said second object; coolingthe expanded material while the material is moving along said surfacearea of said second object to a temperature at which the material is nolonger pliable but is substantially rigid; removing continuously adifferential section of the expanded material from said second object;and cutting finite lengths of the material from the continuous length ofmaterial when removed from said second object, each finite length havinglateral edges thereof stretched to curved configurations of differentarc length.
 7. The method of claim 6 wherein: said first object is arotatable cylindrical roll and said second object is a rotatable conicalroll and wherein the surface of the material heated to the coolertemperature does not contact the surface of said second roll as thematerial passes thereover.
 8. The method of claim 7 wherein: saidsurface of said second object is defined by a plurality of spaced apartmembers extending laterally across the material, and wherein saidcooling is accomplished by directing separate streams of a chillingfluid against both sides of the material as the material passes oversaid surface of said second object.
 9. The method of claim 8 wherein:said separate streams of said chilling fluid are formed by: initiallyestablishing a single stream of chilling fluid; flowing said singlestream toward the outer surface of said second object; dividing saidsingle stream into two substreams; directing one substream onto theouter surface of said second object to cool the outside surface of thematerial; directing a second substream through the openings in saidsurface of said second object between said spaced apart members whichare not covered by the material; and flowing the second substream ofchilling medium over the inside surface of the material supported onsaid spaced apart members defining the surface of said second object;whereby both sides of the expanded material are simultaneously cooledwhile moving along a substantial portion of said surface area of saidsecond object.
 10. The method of expanding a continuous length ofpolyvinyl butyral as defined in claim 1 wherein: the polyvinyl butyralhas a tinted band along a lateral edge of one side thereof, wherein saidside having the tinted band therealong is heated to a temperature ofabout 150* F, in said heating step, and wherein said side not having thetinted band therealong is heated to a temperature of about 170* F, insaid heating step.